I have a three and a half inch touchscreen on a Raspberry Pi 3. The case is made from glow-in-the-dark PLA that I 3D printed.
The OS is raspbian with desktop. I run a browser in kiosk mode and I have it pointed at a couple web pages. The one in the screen shot is twin galaxies.
Some of the other pages are a weather station, a clock, and an airplane radar setup that I have.
NeverEnding fun in the land of raspberry pi.